-68 CRETACEOUS ROCKS OF S. INDIA. [PaRT II. § 1. 



a small quarry in the Trichinopoly beds, (here also limestone,) I found 



a layer of the pisolitic rock, about 6 inches thick, 

 Mode of occurrence. 



beneath the cotton soil, and resting on about 2 feet 



of little rolled fragments of the different varieties of the limestones. 



The nuclei of the individual nodules are most frequently mere grains, 



and the nodules from the size of a pea to that of a 

 Structure. 



hazelnut, but sometimes the rock is made up of 



limestone fragments of all sizes, up to 4 or 5 inches in diameter, and, not 



unfrequently, masses of the pisolite itself are seen imbedded in a more 



recent formation of similar nature. TJiis rock, although more abundant 



here than elsewhere, is by no means peculiar to this ridge. It is met 



with, for instance, on the Ootatoor limestone of Olapaudy, and to some 



extent on the Cullygoody ridge. Limestone blocks, both of the coral reef 



and purer sedimentary varieties, are also occasionally found with a similar 



calcareous coating one or two inches thick, in which the pisolitic structure 



is laro'ely seen, and where it is difficult to imagine that any accumulation 



of calcareous matter could take place mechanically or chemically. 



That this rock is of sub-aerial and recent formation there can be 



little doubt, for it occurs, coating the limestones, in 

 Of recent formation. i • ^ 



situations where no accumulation of water is 



possible. Moreover, in a specimen presented by Mr. Cunliffe to the 



Geological Museum, a specimen of Helix faUaciosa, one of the commonest 



living snails of the country, was thoroughly embedded. There is, however, 



some difficulty in understanding how successive coats of calcareous 



matter could be deposited round a number of nuclei, so as to form 



pisolite, if the nodules were not freely suspended in the formative fluid. 



That the coral-reef hmestone of Cullygoody is of the same age as that 



, ,, ^ „ , at the other localities previously described, I infer. 



Age of the Cu]l3'goody ^ •' 



limestone. foj^. the following reasons : — 



\st. — It resembles the reef limestones of the Ootatoor Group in all its 

 mineral peculiarities, and of the few recognizable fossils which it contains, 



